diff --git a/doc/Building.md b/doc/Building.md
index bfd47937b..ced06b8e0 100644
--- a/doc/Building.md
+++ b/doc/Building.md
@@ -115,7 +115,7 @@ Install the prerequisites using [Homebrew](https://brew.sh/):
 
 ```
 brew install autoconf automake bash binutils cmake coreutils findutils \
-    gnu-getopt libtool make meson nasm ninja pkg-config sdl2 util-linux
+    flock gnu-getopt libtool make meson nasm ninja pkg-config sdl2 util-linux
 ```
 
 You will also have to ensure Homebrew's findutils, gnu-getopt, make & util-linux are in your path, e.g., via